This report describes research done to determine the effect of pipe roughness on orifice meter accuracy. This report specifically analyzes a four-inch diameter tube. Results of the study conclude that tubes of this size can be honed without affecting their accuracy. As an overall conclusion from this and previous studies in normal metering practice, the honing of tubes will not change the coefficient in any pipe size. It is recommended that honing or polishing of meter tubes is permitable and further investigation of roughness effect is no necessary.